Process of removing amorphous wax from petroleum oils



Oct. 15, 1929. R M TRAVIS 1,732,144

PROCESS OF REMOVING AMORPHOUS WAX FROM PETROLEUM OILS Filed July 16, 1927 2 Sheets-Sheet 1 ATTORNEYS Oct. 15, 1929. P M, TRAVIS 1,732,144

PROCESS OF REMOVING AMORPHOUS WAX FROM PETROLEUM OILS Filed July 16. 1927 2 Sheets-Sheet 2 WAX FREE OIL ATTORNEYS '.0 cosity of lubricating UNIT-ED lsifa'ilssA PIERcE nsoN TRAVIS, or Emelwoon, NEw JERSEY; A'ssicNon. 'ro'rnav'ra rxcxss v c'oEronaTIoN, or-'JEE'sEr om', NEW .massima acoBromrIoN ornmwm rnocEss or moms monrnous vvAxfI-noir rE'rnoLEux ons Application led July 1B,

This invention relates to improvements in treating petroleum oils -and' frac'tions thereof containing amorphous parailine'wax to ef-A feet the removal of the wax therefrom while 5 iii thea'inorphous state. vThe processgof'the invention is of special value and application in the treatment of petroleum `oilscontaining lubricating oil constituents and. amorphous wax and rovides ai-simple .and economical 'm process a apted to remove the amorphous wax continuously without a preliminary .treatment that might impair the lubricatingv properties of the oil.

In refining petroleum oils for theproduc- 15 tion'of high grade lubricants it is customaryto distill off the lighter fractions, such as gasoline, kerosene, etc., with steam or at reduced pressure to avoid cracking of the lubricating oil constituents as cracking reduces the visoilI constituents and 'greatly decreases their value. Crude'oil reduced in this manner Vcontains amorphous wax which tends to congeal'at low tempera-- tures. and its presence is therefore obJectionas able in a lubricating oil becauseof the high f our test it gives to the oil.A It is impossible om a practical standpoint to-remov'e the wax while in an amorphous state fromoils of this ,character in the ordinary'ilter .press .o due to rapid plugging of the filtering medium. In order to convert the amorphous wax toa c stalline form so that it might be satisfactor y removed by lilter pressin a high temperature must be employed wli-ic is such vas to greatlyimpair the llubricating properties of the oil.' v

It has been customary in the past to blend oils of this character withia-diluent su'ch'as naphtha, chill the blend to an extremelydnw Q temperature and allow the naphtha-oil s olution to stand for a period of several 'days to permit the wax to settle during which time the entire body of oil mustbe maintained at a temperature of about -10 to 0 F. `This el treatment known as cold settling requires' large storage capacity and an excessive amount of refrigeration.

Attempts have been Vmade to eiect separation of amorphous wax from oils of this char-v IO acter by centrifugal action, `but such opera- 1927. Serial no. $06,333.

'-iATaNr-'oF'i-*ica vcapacit o the machines it has been necessary emp oyand tothediiculties encountered 1n removing the separated wax from the zone' of' centrifugal action. Such :operations iu' the past have either required the use of a' carrier ,liquid to remove-the separatedwax by flotation 1or that the bowl be heatedto melt the wax in order that'it mi ht be' removed in a liquid state. The use o ra carrier liquid has the disadvantage that the carrier liquid itself iust befchilled to the same temperature as the oil so lthat a greater. refrigerating capacity is required and the wax after separationfrom the oil must .be dehydrated.

Further, the presence of a carrier liquid in the bowl of a centrifuge of limited capacity materially decreases the amount of oil that -an be handled. Heating the bowl while roi tating at highspeeds involves diilicult problems in -heat transferand increases the rey capacity lnecessary to ,maintain 'geratin the bowl c argeat the temperature required for eective separation of the oil and wax.

The present inyention provides an imp'oved process whereby amorphouswax may Separated from oils containing it bycentrifugal force andthe separated wax discharged continuously froin the zone of centrifu al actionv withoutthe use :of a carrier liqui or the application of heat toany part of the charge within the zoneof centrifugal f action. According to the. resent invention the oil to be treated', whic has preferably been given a reliminary treatment -sucli as i treatment .wit 66 Baumel sulfuric acid or filtering, to remove as'phaltic` constituents and other impurities which act as protective colloids tending to prevent coalescence of the minute wax particles to form lar er particles,

is blended vvith a diluent material such as a closely cut low end boilingpoint naphtha distillate and the blend so produced heated to av temperature of approximately 100 F. to insure all of the wax present passing into solution in the diluent. 'The mixture is then gradually cooled to a ltemperature of about l0 F. and mildly agitated duringl chilling operation. The chilled nap the l thaweb' 23 and rotatably mounted on the shaft oil'solutiomis ,tl/ien subjected to centrifugal' force to elfectfthe separation of the wax `from the na-phtha-oil solution and the separated wax mechanically discharged in a continuous manner from the zone of centrifugal action at one point with movement toward the axis of rotation while the wax free naphtha-oill solution is discharged.continuously therefrom in a similar manner at another point.

The blending naptha-may be subsequently separated from the wax free oil by distillation and recovered for further use as a diluent.

The process of the invention may be further described in connection with the accompanying drawings which illustrate in a somewhat conventional manner one form of apparatus adapted for the practice of the improved prothat the invention is not limitedthereto'.

cess of the invention, but it is intended and will be understood that this vfurther description is for the purpose of exempliication and In the drawings:

Fig. 1 is a somewhat diagrammatic repre sentation in elevation of an arrangement of apparatus adapted for the practice oof the improved process of the invention.- Fi 2 is an elevation partl in section of one orm of centrifuge suita le for use in lthe arrangement illustrated-in Fig. 1.

Fig. 1 of the drawings shows a storage tank 1 connected through pump 2 and line 3`with a heat insulated mixing tank 4 having a heating coil 5 and stirring device 6 arranged therein. The mixing tank 4is also provided '.-with a valved inlet connection 7 through which a diluenttmate'rial such as a naptha f distillate may bev introduced as desired. Valveddraw-oii' connection 8 and pump 9 are arranged to Withdraw liquid fromI the mixing tank 4 and convey it to the 'insulated cooling tank 10 provided with coil 11 through whicha suitable cooling medium may be circulated. Cooling tank 10 is also equipped al stirring device 12. Conwith a mechanic nectipns 13, 14 and pump 15 are arranged to supply cool oil from .the cooling tank 10 to vthe centrifuge 16. Valved connection '13? may advantageously be provided to withdraw material discharged from the centrifuge to the conveyor 21.

. The centrifuge illustrated in Fig. 2 'comprises a bowl 22 supported by supporting lmeans-1.

24.' A spider 25 held in place by the collar i 26 is arranged to steady the'end of the bowl 22 opposite to the supporting web 23. The

element 27 is keyed vto the shaft 24 and is provided at its outerfsurface with` an extension 28 [which is helical in form and extends approximately to the inner surface of the bowl 22. "The central portion of lthe bowl 22 is cylindrical in form tapering 'toward the shaft at one end. The other end of the bowl is provided with a ring 29 extending in? wardly from the peripheryof the bowl. The

tapered end of the bowl is continued until.

provided-with a series of openings '30l around its periphery at one end beyondthe ring 29. The shaft 24 is supported by the bearings 31 and may be driven directly fromany suitable source of power, for example, by a silent l chain engaging the sprocket 32. The bowl 22 is driven through supporting web 23 by the sleeve 33, for example,fby a silent chain engaging the sprocket 34. In the arrangement illustratedsprocket 34 is slightly larger than the sprocket 32 so that while the bowl 22 and the helix 28 rotate in the same direction, the bowl will rotate at a slightly lower speed. -While both the bowl 22 and the helix 28 rotate at high speed the dierential between them is relatively small so that any diiiiculties incident to the provision and care of a high speed bearing between the shaft 24 and -the sleeve 33 are eliminated. The direction and speed of Arotation of the helix 28 relative to that of the bowl 22-'is such that the helix will operate to ldischarge continuously at the tapered end of the bowl any solid material lwhich would4 otherwise accumulate therein, forV example, the bowl may lbe driven at 1500 to 1800 R. P. M: and the helix at v1550 to 1850 R. P. M. Collecting rings 34- and 35 are provided at opposite ends of .the bowl to collect the wax free naptha-oilsolution and separated solid matel rial as they are discharged from the bowl. A stalling box 36 is arranged to prevent leakage of the material which is introduced through the interior of the hollow shaft 24.

In the operation of the apparatus described and illustrated in accordance with the immixturev is then heated to a temperature'of about 100i F.. and' thoroughly agitate'dto insure all of the amorphouswax passing into solution in the naptha' distillate. -The nap- A-tha-oil` solution is then transferred to the cooling tank where its temperature is gradually reduced to approximately 10 F. bvl circulating a cooling me'dium'such as cold calcium Ichloride brine through the cooling. coil 11. The naptha-oil solution is preferably at intervals by means'of a.

agitated mildly mechanical stirring device 12 during the cooll element 27 and is discharged to` the -interior Aao . ingoperation.

of the rotating bowl 22 through a-series of openings 38 where it is subjected to centrifugal foice. The centrifugal force to which the mixture is subjected is many times greater than the force of gravity and causes the wax which is heavier than thenaptha-oil solution to separate therefrom forming an outer layer" 2'5which is mechanically conveyed to the tapered Iend of the bowlv bythe helix 28 where it is discharged from the bowl continuously.l

- The motion of the helix relative to the bowl is not sufficient to actpositively on the liquid,

due to its greater fluidity so tha-tthe inner layer of clear cold liquid will flow through the bowl` axially in a direction oppositeto the motion o f'the'outer layer of wax, passing over the inneredge of the ring 29 as it is dis! placed by fresh oil supplied to the bowl. As

the wax is mechanically conveyed by the helix 28 to ajpoint nearer the axis of rotation than the point "at which the naptha-oil solution is discharged, while still subjected 'to the action of centrifugal force, the last traces of the oil or naptha-oil solution may be separated therefrom so that a maximum yield of wax free oil and a high 'melting point wax may be obtained. The speed at which the bowl may most advantageously be driven will vary somewhat with the character ofl the oil, the

vrate at'which the oil is introduced thereto-v andthe length ofthe bowlemployed. In

` general, a lower speed is permissiblev with a to effect satisfactory separationr of the wafx from anaptha-oil solution supplied thereto atL a rate of 2000 to 8000i gallons per hour,

thoughhigher speeds may be employed Uto insure 'the separation of Athe lasttraces of wax.' Where higher speeds" are employeda higlirxr iiielting jointwax ill be obtained. I ere arefin ry has a' p ant equipped for v"the `old"g 1;ravity method-of cold settling the process ofthe invention may be employed in conjunction` therewith. `For example, the, l cooled solution may be allowed to stand for aV Itime before centrifuging to effect a preliminary 'concentration of the Wax byfsettling.

A layer of cool clear liquid may -then bedrawn off from the upper part of the settledliquid body'. and the remainder of the naptha-oil solution containing the wax concentrated therein by settling, centrifugally treated as above described.- f l In refineries which are not provided with the equipment for present day cold settling methods the various oils or solutions now subjected to the 'cold settling method of ltreating may betreated continuously-in accordance with lthe present invention while avoiding heavy investment in cold settling tanks and' excessive refrigerating capacity. -The precess of the' invention has the further advantages that the apparatus required is of rugi ged construction and does not require critical adjustments or the supervision of a skilled operator.

' I claim: J

` 1. The improvement in the treatment of 'pjtroleum oils for the removal of amorphous wax contained therein, comprising chilling the oil .to be treated in the presence of a` low` the faxis of rotation at another point. l a 2. The improvementy 'n the treatmentv of L petroleum oils for the removal of amorphous wax contained therein, comprising chilling the oil to be tr-:ated inthe presence of a low boiling naptha distillate and subjecting the yboiling .diluent and subjecting: the chilled l v in a continuous manner ion vterial from saidzone with movement toward i chilled Imixture to centrifugal force whereby V the wax and wax free naptha-oil solution are separated intovlayers, mechanically discharging thewax in a continuous manner from the zone in which it is subjected to 'centrifugal force at' one point with movement toward tli/e chilled mixture to centrifugal force,` whereby .the wax and wax rfree naptha-oil solution are separated into layers, causin the wax to move laxially in the zone inw 'ch itis sull jected to centrifugal forceglfand,causingA the wax free naptha-oil solutin -tof-move axially in said zone in the opposite" drecton, niechanica'll'y dischargingthe 'wat i'naf continuaxis of rotation'and continuously discharglon er bowl and with a decrease in the. ratevl fjofintrod'uction of fresh oil. With a bowl l 15'." in diameter and 45 ylong a rotative speed fof 1500, R.- P. M.' will in most cases be sufficient j lll the treatment of I a boiling lnaptha distillate, subjecting-the A other point.

, 4. The improvement in the .treatment of petroleum oils for the removal of amorphous wax contained therein, comprising heating .the oil to be treated inthe presence of a low boiling naptha distillate' and subsequently chilling the admixed oil and diluent to a tem- A perature below F.1,subjecting the chilled y:ze

- the axis of rotation and continuously mixture to centrifugal force whereby the wax and Wax free naptha-oil solution are separated` into layers, mechanically discharging the wax in a continuous manner Afrom the zone in which it is subjected to centrifugal force. at one point with movement towrd 1scharging the wax free naptha-oil so ution from said zone with movement toward the axis of rotation at another point.

5. The improvement in the treatment of petroleum oils for the removal, of amorphous waxk contained therein, comprising `chilling the oil to be treated in the presence of a lowI boiling napthak distillate, subjecting the chilled mixture to centrifugal force, whereby the wax and Wax free naptha oil solution are separated into layers,- continuously discharging the wax free.napthaoil solution from the zone inl which itis subjecteddto centrifugal 1,-.) force at one point with movement toward the axisl of rotation, and mechanically dischargpoint.'

ing wax in a continuous manner from said zone with movement toward the axis of.v rotation at a point nearerto said axis than the point at which the Waxv free naptha-oil solui 6. The improvement in the treatment of petroleum oils for the removal of amorphous rara-2,144

the oil to be treated in the presence of a low boiling naptha distillate to a temperature below 0 F., subjecting'the chilled mixture to centrifugal force whereby the wax and wax free naptha-oil'solution are separated into layers, mechanically discharging the wax in a continuous manner from the zone in which it is subjected to centrifugal force l at one point withmovement toward the axis of rotation and continuously discharging the Wax free naptha-oil solution from said zone with movement toward the axis of -rotation at another point.

8. The improvementl in the treatment of petroleum oils for the removal of amorphous Wax contained therein, comprising' chilling the oil to be treated in thepresence of a low boiling diluent and subjecting the chilled mixture to centrifugal force in a separating zone, whereby the'wax and solution of wax free oil and diluent are separated into llaya been partially separated to move axiallys in the separating zone while subjected to the action of centrifugal `nforce, mechanically conveying wax subsequently separating from the partially clarified oil axially in the opvposit-ely direction, continuously discharging the wax from the zone in which it'is'subjectked to centrifugal'n fprce at one pointwith movement toward the axis of rotation, and continuously. discharging the wax free oil and diluent material from said zone with movec ment toward the axis of. rotation to another In testimony whereofI aiiix my signature.`.

PIHERCE MASON TRAVIS.

wax contained therein,comprising chilling the' oil to be treated to below 09 F. in the I' ing afbody of? the chilled mixture to a jsettling operation subsequently drawing olf a 4 ,layer of clear liquid from theupper porfsb ment toward point.

. tion of wax free. *oil and diluent" material are separated intov layers, mechanically 'discharging the wax in a continuous manner from'the zone in which it is subjected to presence of a low boiling diluent, subjectcentrifugal force .at one point with movementtoward the axis. of rotation and continuously discharging the wax free oil and diluent material from said zone with movethe axis of rotation at another 7i The im rovement inthe treatment 0f4 petroleum oi for the removal of amorphous- 

